/*
 * File      : ymodem.c
 * COPYRIGHT (C) 2012, Shanghai Real-Thread Technology Co., Ltd
 *
 * Change Logs:
 * Date           Author       Notes
 * 2013-04-14     Grissiom     initial implementation
 */

#include <rthw.h>
#include "ymodem.h"

static const rt_uint16_t ccitt_table[256] = {
	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
	0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
	0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
	0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
	0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
	0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
	0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
	0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
	0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
	0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
	0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
	0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
	0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
	0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
	0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
	0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
	0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
	0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
	0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
	0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
	0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
	0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
	0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
	0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
	0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
	0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
	0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
	0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
	0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
	0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
	0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
	0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
};
rt_uint16_t CRC16(unsigned char* q, int len)
{
	rt_uint16_t crc = 0;

	while(len-- > 0)
		crc = (crc << 8) ^ ccitt_table[((crc >> 8) ^ *q++) & 0xff];

	return crc;
}

// we could only use global varible because we could not use
// rt_device_t->user_data(it is used by the serial driver)...
static struct rym_ctx* _rym_the_ctx;

static rt_err_t _rym_rx_ind(rt_device_t dev, rt_size_t size)
{
	return rt_sem_release(&_rym_the_ctx->sem);
}

/* SOH/STX + seq + payload + crc */
#define _RYM_SOH_PKG_SZ (1+2+128+2)
#define _RYM_STX_PKG_SZ (1+2+1024+2)

static enum rym_code _rym_read_code(
    struct rym_ctx* ctx,
    rt_tick_t timeout)
{
	/* Fast path */
	if(rt_device_read(ctx->dev, 0, ctx->buf, 1) == 1)
		return *ctx->buf;

	/* Slow path */
	do {
		rt_size_t rsz;

		/* No data yet, wait for one */
		if(rt_sem_take(&ctx->sem, timeout) != RT_EOK)
			return RYM_CODE_NONE;

		/* Try to read one */
		rsz = rt_device_read(ctx->dev, 0, ctx->buf, 1);

		if(rsz == 1)
			return *ctx->buf;
	} while(1);
}

/* the caller should at least alloc _RYM_STX_PKG_SZ buffer */
static rt_size_t _rym_read_data(
    struct rym_ctx* ctx,
    rt_size_t len)
{
	/* we should already have had the code */
	rt_uint8_t* buf = ctx->buf + 1;
	rt_size_t readlen = 0;

	do {
		readlen += rt_device_read(ctx->dev,
		                          0, buf + readlen, len - readlen);

		if(readlen >= len)
			return readlen;
	} while(rt_sem_take(&ctx->sem, RYM_WAIT_CHR_TICK) == RT_EOK);

	return readlen;
}

static rt_size_t _rym_putchar(struct rym_ctx* ctx, rt_uint8_t code)
{
	rt_device_write(ctx->dev, 0, &code, sizeof(code));
	return 1;
}

static rt_err_t _rym_do_handshake(
    struct rym_ctx* ctx,
    int tm_sec)
{
	enum rym_code code;
	rt_size_t i;
	rt_uint16_t recv_crc, cal_crc;

	ctx->stage = RYM_STAGE_ESTABLISHING;

	/* send C every second, so the sender could know we are waiting for it. */
	for(i = 0; i < tm_sec; i++) {
		_rym_putchar(ctx, RYM_CODE_C);
		code = _rym_read_code(ctx,
		                      RYM_CHD_INTV_TICK);

		if(code == RYM_CODE_SOH)
			break;
	}

	if(i == tm_sec)
		return -RYM_ERR_TMO;

	i = _rym_read_data(ctx, _RYM_SOH_PKG_SZ - 1);

	if(i != (_RYM_SOH_PKG_SZ - 1))
		return -RYM_ERR_DSZ;

	/* sanity check */
	if(ctx->buf[1] != 0 || ctx->buf[2] != 0xFF)
		return -RYM_ERR_SEQ;

	recv_crc = (rt_uint16_t)(*(ctx->buf + _RYM_SOH_PKG_SZ - 2) << 8) | *(ctx->buf + _RYM_SOH_PKG_SZ - 1);
	cal_crc = CRC16(ctx->buf + 3, _RYM_SOH_PKG_SZ - 5);

	if(recv_crc != cal_crc)
		return -RYM_ERR_CRC;

	/* congratulations, check passed. */
	if(ctx->on_begin && ctx->on_begin(ctx, ctx->buf + 3, 128) != RYM_CODE_ACK)
		return -RYM_ERR_CAN;

	return RT_EOK;
}

static rt_err_t _rym_trans_data(
    struct rym_ctx* ctx,
    rt_size_t data_sz,
    enum rym_code* code)
{
	const rt_size_t tsz = 2 + data_sz + 2;
	rt_uint16_t recv_crc;

	/* seq + data + crc */
	rt_size_t i = _rym_read_data(ctx, tsz);

	if(i != tsz)
		return -RYM_ERR_DSZ;

	if((ctx->buf[1] + ctx->buf[2]) != 0xFF) {
		return -RYM_ERR_SEQ;
	}

	/* As we are sending C continuously, there is a chance that the
	 * sender(remote) receive an C after sending the first handshake package.
	 * So the sender will interpret it as NAK and re-send the package. So we
	 * just ignore it and proceed. */
	if(ctx->stage == RYM_STAGE_ESTABLISHED && ctx->buf[1] == 0x00) {
		*code = RYM_CODE_NONE;
		return RT_EOK;
	}

	ctx->stage = RYM_STAGE_TRANSMITTING;

	/* sanity check */
	recv_crc = (rt_uint16_t)(*(ctx->buf + tsz - 1) << 8) | *(ctx->buf + tsz);

	if(recv_crc != CRC16(ctx->buf + 3, data_sz))
		return -RYM_ERR_CRC;

	/* congratulations, check passed. */
	if(ctx->on_data)
		*code = ctx->on_data(ctx, ctx->buf + 3, data_sz);
	else
		*code = RYM_CODE_ACK;

	return RT_EOK;
}

static rt_err_t _rym_do_trans(struct rym_ctx* ctx)
{
	_rym_putchar(ctx, RYM_CODE_ACK);
	_rym_putchar(ctx, RYM_CODE_C);
	ctx->stage = RYM_STAGE_ESTABLISHED;

	while(1) {
		rt_err_t err;
		enum rym_code code;
		rt_size_t data_sz, i;

		code = _rym_read_code(ctx,
		                      RYM_WAIT_PKG_TICK);

		switch(code) {
			case RYM_CODE_SOH:
				data_sz = 128;
				break;

			case RYM_CODE_STX:
				data_sz = 1024;
				break;

			case RYM_CODE_EOT:
				return RT_EOK;

			default:
				return -RYM_ERR_CODE;
		};

		err = _rym_trans_data(ctx, data_sz, &code);

		if(err != RT_EOK)
			return err;

		switch(code) {
			case RYM_CODE_CAN:

				/* the spec require multiple CAN */
				for(i = 0; i < RYM_END_SESSION_SEND_CAN_NUM; i++) {
					_rym_putchar(ctx, RYM_CODE_CAN);
				}

				return -RYM_ERR_CAN;

			case RYM_CODE_ACK:
				_rym_putchar(ctx, RYM_CODE_ACK);
				break;

			default:
				// wrong code
				break;
		};
	}
}

static rt_err_t _rym_do_fin(struct rym_ctx* ctx)
{
	enum rym_code code;
	rt_uint16_t recv_crc;
	rt_size_t i;

	ctx->stage = RYM_STAGE_FINISHING;

	/* we already got one EOT in the caller. invoke the callback if there is
	 * one. */
	if(ctx->on_end)
		ctx->on_end(ctx, ctx->buf + 3, 128);

	_rym_putchar(ctx, RYM_CODE_NAK);
	code = _rym_read_code(ctx, RYM_WAIT_PKG_TICK);

	if(code != RYM_CODE_EOT)
		return -RYM_ERR_CODE;

	_rym_putchar(ctx, RYM_CODE_ACK);
	_rym_putchar(ctx, RYM_CODE_C);

	code = _rym_read_code(ctx, RYM_WAIT_PKG_TICK);

	if(code != RYM_CODE_SOH)
		return -RYM_ERR_CODE;

	i = _rym_read_data(ctx, _RYM_SOH_PKG_SZ - 1);

	if(i != (_RYM_SOH_PKG_SZ - 1))
		return -RYM_ERR_DSZ;

	/* sanity check
	 *
	 * TODO: multiple files transmission
	 */
	if(ctx->buf[1] != 0 || ctx->buf[2] != 0xFF)
		return -RYM_ERR_SEQ;

	recv_crc = (rt_uint16_t)(*(ctx->buf + _RYM_SOH_PKG_SZ - 2) << 8) | *(ctx->buf + _RYM_SOH_PKG_SZ - 1);

	if(recv_crc != CRC16(ctx->buf + 3, _RYM_SOH_PKG_SZ - 5))
		return -RYM_ERR_CRC;

	/* congratulations, check passed. */
	ctx->stage = RYM_STAGE_FINISHED;

	/* put the last ACK */
	_rym_putchar(ctx, RYM_CODE_ACK);

	return RT_EOK;
}

static rt_err_t _rym_do_recv(
    struct rym_ctx* ctx,
    int handshake_timeout)
{
	rt_err_t err;

	ctx->stage = RYM_STAGE_NONE;

	ctx->buf = rt_malloc(_RYM_STX_PKG_SZ);

	if(ctx->buf == RT_NULL)
		return -RT_ENOMEM;

	err = _rym_do_handshake(ctx, handshake_timeout);

	if(err != RT_EOK)
		return err;

	err = _rym_do_trans(ctx);

	if(err != RT_EOK)
		return err;

	return _rym_do_fin(ctx);
}

rt_err_t rym_recv_on_device(
    struct rym_ctx* ctx,
    rt_device_t dev,
    rt_uint16_t oflag,
    rym_callback on_begin,
    rym_callback on_data,
    rym_callback on_end,
    int handshake_timeout)
{
	rt_err_t res;
	rt_err_t (*odev_rx_ind)(rt_device_t dev, rt_size_t size);
	rt_uint16_t odev_flag;
	int int_lvl;

	RT_ASSERT(_rym_the_ctx == 0);
	_rym_the_ctx = ctx;

	ctx->on_begin = on_begin;
	ctx->on_data  = on_data;
	ctx->on_end   = on_end;
	ctx->dev      = dev;
	rt_sem_init(&ctx->sem, "rymsem", 0, RT_IPC_FLAG_FIFO);

	odev_rx_ind = dev->rx_indicate;
	/* no data should be received before the device has been fully setted up.
	 */
	int_lvl = rt_hw_interrupt_disable();
	rt_device_set_rx_indicate(dev, _rym_rx_ind);

	odev_flag = dev->flag;
	/* make sure the device don't change the content. */
	dev->flag &= ~RT_DEVICE_FLAG_STREAM;
	rt_hw_interrupt_enable(int_lvl);

	res = rt_device_open(dev, oflag);

	if(res != RT_EOK)
		goto __exit;

	res = _rym_do_recv(ctx, handshake_timeout);

	rt_device_close(dev);

__exit:
	/* no rx_ind should be called before the callback has been fully detached.
	 */
	int_lvl = rt_hw_interrupt_disable();
	rt_sem_detach(&ctx->sem);

	dev->flag = odev_flag;
	rt_device_set_rx_indicate(dev, odev_rx_ind);
	rt_hw_interrupt_enable(int_lvl);

	rt_free(ctx->buf);
	_rym_the_ctx = RT_NULL;

	return res;
}
